Percussion firing system

ABSTRACT

Percussion firing apparatus for firing an explosive charge in a downhole tool by use of a nonelectrical wireline characterized by positive safety features and including a percussion firing head assembly that is set in the well and, on a subsequent trip, a firing pin assembly is emplaced within the firing head assembly to effect firing of the charge; after which the entire percussion firing apparatus is pulled. The positive safety features provided include (1) preventing the emplacement of an armed firing pin assembly within the receiving chamber of the percussion firing head assembly while running or pulling; and (2) allowing only one firing attempt.

'llarnplen States Patent {54] PERCUSSION FIRING SYSTEM Inventor:

Filed:

Appl. No.: 144,582

Jack W. Tamplen, Rural Route 2,

Celina, Tex. 75009 May 18, 1971 Jan. 16, 1973 Primary Examiner-Verlin R. Pendegrass Atlorney-Wofford. Felsman & Fails. Win. '1. Wof- [57] ABSTRACT Percussion firing apparatus for firing an explosive charge in a downhole tool by use of a nonelectrical wireline characterized by positive safety features and including a percussion firing head assembly that is set in the well and, on a subsequent trip, a firing pin assembly is emplaced within the firing head assembly to effect firing of the charge; after which the entire percussion firing apparatus is pulled. The positive safety features provided include (1) preventing the emplacement of an armed firing pin assembly within the receiving chamber of the percussion firing head assembly while running or pulling; and (2) allowing only one firing attempt.

36 Claims, 7 Drawing Figures PATENTEDJAMsIQYs 3.710 717 sum 2 0F 2 ATTORNEYS PERCUSSION FIRING SYSTEM BACKGROUND OF THE INVENTION for firing an explosive charge means within a wellbore penetrating subterranean formations.

2. Description of the Prior Art The prior art has seen the development of apparatus for firing an explosive charge downhole by wirelines. Such charges were used in a wide variety of applications. For example, setting tools were operated with such charges to set bridge plugs and/or packers; perforating guns were employed to effect communication between the interior of a conduit in a well and the subterranean formations penetrated by the well; and explosive cut-off tools were employed to sever sections of conduit or the like. Primarily, the apparatus for firing an explosive charge has developed along the lines of either electrically fired systems or the nonelectrical wireline systems that resorted to percussion firing of an igniter means. The electrically fired systems require care in connection, handling and transportation, as well as in running, since the electrical system is subject to stray currents, as from radiofrequency transmission towers, static electricity, and the like. Such electrically fired systems are also generally more expensive in operation and are not as readily available in the field as are the nonelectrical wireline units. The percussion firing systems, on the other hand, have required extreme care in handling and have been dangerous because of the danger of an inadvertent blow effecting firing of the charge, either during handling or while being lowered into the well. Moreover, the prior art percussion firing apparatus has been dangerous and unsatisfactory because it could not be ascertained with certainty that it had been fired or disarmed in the wellbore, so that it was risky to go in and retrieve the percussion firing assembly. Expressed otherwise, a sharp blow during the retrieval operation could cause inadvertent firing, sometimes at the incorrect depth with resulting damage to the well casing, or conduit. It will be apparent that such inadvertent firing, when the charge is properly located at the correct depth, is not necessarily disadvantageous, since such firing would still achieve the desired result. The prior art apparatus, however, al-

, lowed a pulling tool or other wireline accessory to move the charge to be fired without disarming the percussion firing apparatus such that the charge could be fired at an improper depth.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a schematic elevational view of a wireline tool of a type which may use this invention, the tool being shown within a cased wellbore.

FIG. 2 is a fragmentary longitudinal sectional view of the upper part of the percussion firing head assembly of FIG. 11.

FIG. 3 is a fragmentary longitudinal sectional view of the middle part ofthe percussion firing head assembly of FIG. 1.

FIG. 4 is a fragmentary longitudinal sectional view of the bottom part of the percussion firing head assembly of FIG. 1.

FIG. 5 is a fragmentary longitudinal sectional view of an armed firing pin assembly emplaced in the upper part of the percussion firing head assembly of FIG. 2.

FIG. 6 is a cross sectional view taken along the line VI VI ofFlG. 5.

FIG. 7 is a schematic view of an unfolded exterior of the body illustrated in FIG. 3 showing the .I-slot arrangement for controlling the means for setting the slips.

DESCRIPTION OF PREFERRED EMBODIMENTS It is an object of this invention. to provide one or more of the following desirable features not heretofor provided:

l. a percussion firing apparatus wherein a tool containing an explosive charge, without a firing means is first run in and set in a conduit in the wellbore with a shear down running too]; and a firing means is then run into the tool which is fired on a second trip for safety; the running in of the firing means, the firing and the pulling being effected by a shear up pulling tool;

2. a percussion firing apparatus that allows only one firing blow on the firing means in an attempt to fire the explosive charge and thereafter disarms the firing' means so that the apparatus may be safely retrieved in the disarmed condition in the event there is a misfire; and

3. a percussion firing apparatus that prevents engagementof a pulling tool until the firing pin assembly has been disarmed, as by firing the explosive charge, for safety in retrieving the apparatus.

These and other specific objects will be apparent from the following descriptive matter when taken in conjunction with the drawings.

Referring to the drawings, FIG. 1 illustrates a percussion firing head assembly 11, a setting tool 13 and a bridge plug 15, all of which are removably attached to a running tool 17 and suspended by a tool string 19 from a nonelectrical wireline 21 in a section of conduit 23 such as casing in a cased wellbore 25.The elements other than the percussion firing head assembly 11 are conventional and need not be described in detail herein. For example, the bridge plug 15 and the setting tool 13 are described in US. Pat. Nos. 3,186,485 and 3,266,575, issued to H. D. Owen. It is sufficient to note that when an explosive charge within the setting tool is fired the bridge plug is set in the conduit 23 by the setting tool; and the setting tool 13 thereafter shears a shear pin to separate from the bridge plug 15. The setting tool 13 may then be pulled] from the wellbore 25. The setting tool 13 may be fired in response to the firing of an explosive charge such as an igniter means in the percussion firing head assembly 11.

As illustrated, the percussion firing head assembly 11, withthe setting tool 13 and the bridge plug 15 attached thereto, is being emplaced .at a predetermined depth in the wellbore 25 with a shear down running tool. Such shear down running tools are conventional and have the characteristic that when jarred downwardly to produce a large force, a shear pin is sheared to release the tool from any device with which it is connected such as the percussion firing head assembly 11. Conversely, a shear up tool has the characteristics that it will shear a shear pin and release any device with which it is connected when a sufficiently large upwardly acting force is developed, as by being jarred upwardly. The shear down running too] and the shear up pulling tool are employed conventionally with a tool string that has means such as jars for developing upwardly and downwardly acting forces. Moreover, the running and pulling tools have means for engaging the fishing neck means of the percussion fir-- ing head assembly 11. After the percussion firing head assembly 11 is emplaced in the conduit 23, a firing pin assembly is inserted on a second trip and the explosive charge fired to actuate the setting tool and set the bridge plug in place. After the bridge plug is set, the setting tool is sheared off and pulled from the wellbore 25; and the bridge plug is left in the well. If the setting tool 13 fails to shear completely free of the bridge plug 15, it may be sheared therefrom by a jarring force transmitted through the shear up pulling tool, because of the preselected relative sizes of the respective shear pins.

Referring to FIGS. 2-4, the percussion firing head assembly 11 comprises a fishing neck means 27, firing pin assembly receiving chamber 29, igniter means 31, settable hanging means 33 and first connection means 35.

j The fishing neck means 27 is disposed at the upper end of the percussion firing head assembly 1 1. The fishing neck means 27 may comprise either an internal or an external fish neck. As illustrated, the fishing neck means 27 comprises an internal fishing neck means that is adapted for being suspended from a running or a pulling tool. Specifically, the fishing neck means 27 is adapted for being suspended from a shear down" running tool and for being engaged and pulled upwardly by a shear up pulling tool.

The firing pin assembly receiving chamber 29 is disposed adjacent the fishing neck means 27. It has a length L, and is adapted for receiving a firing pin assembly. Specifically, the firing pin assembly receiving chamber 29 is substantially cylindrical in its internal configuration for receiving a substantially cylindrical firing pin assembly, although any compatible configuration may be employed.

The igniter means 31 comprises a small explosive charge such as igniter 37 and is disposed beneath the firing pin assembly receiving chamber 29 so as to be ignited responsive to a downwardly moved firing pin in a firing pin assembly emplaced in the firing pin assembly receiving chamber. A safety disc 38 is disposed above the igniter 37 to prevent firing. As illustrated, the igniter 37 has an upper flange 39 that is received in a removable ejector cap 41. The ejector cap 41 is disposed on top of a receiver 43 that carries the igniter 37. Thus, the ejector cap 41 will pull the igniter 37 from the receiver 43 when the ejector cap 41 is lifted from the top of the receiver 43. This provides a convenient way of removing the igniters and provides an additional safety factor when a misfiring of an igniter has occurred; since rodding from the bottom, as would otherwise be necessary, is dangerous. The ejector cap 41 is received in a recess in a sub 45 that is removably connected, as by threaded connection, with the receiver 43 for retaining the ejector cap 41 in place.

The settable hanging means 33 is provided for suspending the percussion firing head assembly in the conduit 23. As illustrated, the settable hanging means comprises drag shoe means 47 and slip means 49. The drag shoe means 47 contain a guide means such as guide pin 51 that engages a J-slot arrangement 53, but is otherwise freely movable reciprocally along the portion 55 of the percussion firing head assembly 11. The guide pin 51 is retained in place by a band 52 that is rotatably disposed within drag shoe housing 54. Ex-

pressed otherwise, the drag shoe means 47 is freely movable rotationally about pin 51. The drag shoe means 47. has drag shoes 57 that are biased outwardly by springs 59 for frictionally dragging on the walls of the conduit 23. The drag shoes 57 have, at each end, an extending lip 61 that prevents their being pushed out of the drag shoe means 47 by the spring means 59. The guide pin 51 serves to limit the upward and downward movement of the drag shoe means 47, depending upon which slot it engagesFThe .I-slot arrangement 53 and the guide pin 51 allow an operator at the surface to control setting of the slip means 49 by reciprocal movement of the percussion firing head assembly 11 within the conduit 23, as will become more clearly apparent from the operational description hereinafter.

As illustrated in FIG. 7, the .I-slot 53 is cut peripherally around the portion 55 of the percussion firing head assembly, illustrated therein in unfolded format. The J-slot 53 is continuous peripherally around the portion 55 for guiding the guide pin 51 through repetitive traverses through 360 around the portion 55. The J-slot 53 has an entry slot 63 for entry of the guide pin into the .I-slot arrangement. The .I-slot 53 also has an elongate upwardly extending slot 65 for allowing the guide pin 51 to move upwardly for setting the slip means 49.

The slip means 49, FIG. 3, are connected with the drag shoe means 47 so as to be moved upwardly and downwardly responsive to the respective movement of the drag shoe means. Expressed otherwise, the drag shoes 57 frictionally drag on the walls of the conduit 23 and bias, through their frictional force, the drag sh'oe means upwardly or downwardly as the tool is moved respectively downwardly or upwardly. The slip means 49 follow the movement of the drag shoe means 47. An inverted cone means such as cone 67 is disposed adjacent the slip means when the slip means are at their lower point. The inverted cone 67 is adapted for upward travel of the slip means 49 thereon for extension of the slip means 49 outwardly to engage the walls of the conduit 23 in the well for hanging the percussion firing head assembly 11 in the conduit 23. Expressed otherwise, the slip means 49 are set, or en gaged with the conduit, by downward movement of the percussion firing head assembly 11 when the guide pin 51 is in the upwardly extending slot 65, FIG. 7, allowing the slip means 49 to run up on the inverted cone 67. The slip means are more rigidly set by a downward force. Conversely, the slip means 49 are released by an upward force on the percussion firing head assembly, pulling the inverted cone 67 from beneath the slip means 49.

The first connection means 35, FIG. 4, is provided for connection with a device that is actuated responsive In addition to the foregoing essential elements in the percussion firing assembly 11, it has been found advantageous to provide a hammer pin means 71 that is disposed intermediate the firing pin in the firing pin assembly and the igniter means 31. The hammer pin means 71 is located so as to be struck by the firing pin and, in turn, strike the igniter 37 for ignition of the igniter. If desired, the hammer pin means 71 can be an integral part of the firing pin assembly. As illustrated, however, it is disposed at the lower end of the firing pin assembly receiving chamber 29. The hammer pin means 71 includes a hammer pin 73 and a hammer pin retainer 75. the hammer pin 73 has a lower firing tip 77 for transmission of a sharp downward force to fire the percussion cap 79 in the igniter 37. The hammer pin retainer 75 has an internal recess 81 that receives the flanges 113 of the hammer pin for retaining the hammer pin 73 in place. The hammer pin retainer 75 is received in a recess 35 in sub 15. The hammer pin retainer 75 extends upwardly to form internal cut away cylinder 37 and is retained in place by upper sub 97.

Slot means 89, FIGS. 2, and 6, are disposed adjacent the hammer pin retainer and communicate between the interior and exterior of the percussion firing head assembly for allowing trash, debris, and the like to pass outwardly into the wellbore 25. The

hammer pin retainer 75 has downwardly and outwardly sloping surfaces defining a trough 91, FIG. 6, to facilitate outward passage of the trash from over the hammer pin 73. The slot means 89 and the trough 91 are defined by columns 93 and 94 of the respective sub 45 and hammer pin retainer 75. The sub 45 is connected with the upper sub 97, FIGS. 2 and 5, by threaded connections 99. The hammer pin retainer 75 provides support shoulder portion 101, FIGS. 5 and 6, for supporting a firing pin skirt 133 and preventing contact of the firing pin 1115 with the hammer pin 73. Since the trash, debris, and the like are drained from over the hammer pin 73, less chance of misfiring is realized. Expressed otherwise, the absence of trash between the firing pin 1115 and the hammer pin 73 increases the likelihood that the sharp downward force which moves the firing pin 1115 downwardly will effect ignition of the igniter 37.

In addition to the separate hammer pin means, it has been found advantageous to emplace the igniter means 31 at the upper portion of the percussion firing head assembly for a top firing tool. An elongate detonation passageway 1117, FIGS. 2-4, is disposed intermediate the igniter means 31 and the first connection means 35 for downward passage of the shock wave from the ignition of the igniter 37. When an elongate detonation passageway 107 is employed, it is frequently preferably to also employ a shooting adapter 109 and a booster pellet 111 at the lower end of the detonation passageway, FIG. 41. The shooting adapter 109 has a third connection means such as threads 113, similar to the first connection means 35, for connection with a device to be actuated in response to ignition of the booster pellet 1 11. The booster pellet 1 11 increases the likelihood that the device that is to be actuated will be actuated in response to ignition of the igniter 37. g

If desired, an elongated firing pin assembly and an elongated firing pin assembly receiving chamber can be employed and eliminate the necessity for the detonation passageway 1117.

As indicated, and as illustrated in FIG. 5, a firing pin assembly 115 is run into the wellbore and inserted into the firing pin assembly receiving chamber 29 on a second trip. The firing pin assembly 115 is adapted to be inserted through the fishing neck means 27 and into the firing pin assembly receiving chamber 29. The firing pin assembly 115 includes a second connection means 1 17, a firing pin 105, and an arming means 119.

The second connection means 117 is disposed at the upper end of the firing pin assembly 115 and is adapted for connection with a borehole tool that is capable of transmitting a sharp downward force such as may be developed by jars in a tool string. The sharp downward force must be great enough to effect downward movement of the, firing pin, as described hereinafter with respect to FIG. 5. Ordinarily, it is economically advantageous if the borehole tool is wireline wirelike tool.

Preferably, and as illustrated, the second connection means 1 17 comprises a male thread of a threaded connection for connecting with the bottom female thread of a shear up wireline pulling tool.

The firing pin is disposed within the firing pin assembly and has a chamfered lower end 121 that is adapted for striking the hammer pin 73.

The arming means 119 connects the firing pin 105 with the second connection means 117, when armed, such that the firing pin 1115 can be forced downwardly by a sharp downward force that is imparted to the second connection means 117, as by jarring downwardly with a wireline tool. When armed, the arming means effects a length L for the firing pin assembly. The arming means 119 includes a single-fire safety means that is interposed intermediate the firing pin and the second connection means. The single-fire safety means allows arming the firing pin assembly such that the sharp downward force on the second connection means 117 will cause the firing pin 105 to attempt ignition of the igniter means, as by moving downwardly and striking the hammer pin 73. The single-fire safety means also effects disarming of the firing pin assembly after one such attempt.

The arming means also includes an armed safety means that prevents a pulling tool from engaging the I fishing neck means 27 of the percussion firing head assembly until the firing pin assembly 115 has been disarmed. Specifically, the armed safety means prevents a pulling tool from engaging the second connection means 117 and the fishing neck means 27 simultaneously by having the length L of the firing pin assembly so long with respect to the first length L, of the firing pin assembly receiving chamber 29 that the dogs 123, FIG. 5, of the pulling tool 125 are prohibited from penetrating below the fishing neck means 27 until the firing pin assembly 115 is disarmed, or collapsed.

The relationship of L and L also serves as a means preventing receiving an armed firing pin assembly 115 and the dogs of a running tool 17 simultaneously. Expressed otherwise, the means preventing receiving an armed firing pin assembly 115 and] the running tool 17 simultaneously comprises a firing pin assembly receiving chamber 29 of a first length L that is so short that the firing pin assembly 115; having a second length L from its second connection means 117 to its lower end 121, when armed; cannot fit therewithin so as to allow the running too] 17 to engage the fishing neck means 27. As illustrated in FIGS. 2 and 5', L is, in fact, longer than L,.

The foregoing arming and safety features and means are provided by a firing pin cage 131, a firing pin skirt 133 and a shear pin 135 disposed in an arming aperture 137 that penetrates through the firing pin cage 131 and the firing pin skirt 133, and into at least one side of the firing pin 105.

The firing pin cage 131 is connected with the second connection means 117. As illustrated, the firing pin cage 131 is'integral with the member containing the second connection means 117 to form a unitary piece. The firing pin cage 131 is slidably disposed adjacent the firing pin 105. The firing pin skirt 133 is slidably disposed adjacent the firing pin cage 131 and has limited slidable movementlongitudinally with respect to the firing pin 105. The firing pin skirt 133 prevents physical interaction between the firing pin and the igniter means 37 prior to downward movement of the firing pin 105 with respect to the firing pin skirt 133 to attempt ignition of the igniter means. Specifically, the firing pin 105 is disposed concentrically within the firing pin cage 131 and the firing pin skirt 133 is disposed concentrically about the firing pin 105 and the firing pin cage 131. The shear pin 135 extends through the arming aperture 137 that penetrates through the firing pin cage 131 and the firing pin skirt 133 on at least diametrally opposed sides of the firing pin 105. As illustrated, the shear pin 135 penetrates diametrally through the firing pin 105, the firing pin cage 131 and the firing pin skirt 133.

As indicated hereinbefore and as illustrated in FIG. 5, the firing pin skirt 133 is also disposed peripherally above the hammer pin 73 and resting on shoulder portions 101 when the firing'pin assembly 115 is inserted within the firing pin assembly receiving chamber 29, to prevent the firing pin 105 from contacting hammer pin 73 under the weight of the tool string; and, in turn, depressing the-percussion cap 79 of the igniter means 31. Such depressing of the percussion cap 79 increases the likelihood of misfiring and is undesirable.

The shear pin 135 extending through the arming aperture 137 effects a long combined length L for the armed position, or armed condition, of the firing pin assembly 115;

The shear pin 135 is adapted to shear first between the firing pin cage 131 and the firing pin skirt 133 in order to allow the downward movement of, the firing pin under the sharp downward force imparted to the second connection means 117. The firing pin skirt 133 rests on the shoulder 101 to prevent downward movement of the firing pin skirt and thus enables the shear pin 135 to shear under the sharp downward force. The shear pin 135 then causes the firing pin 105 to move downwardly in response to the sharp downward force that effected the initial shearing of the shear pin 135. The shear pin 135 is adapted to thereafter shear between the firing pin cage and the firing pin to effect a disarmed firing pin assembly 115. In the disarmed condition, the firing pin assembly 115 is shortened and the firing pin 105 no longer is responsively connected with the second connection means 117. This prevents inadvertent later firing of the explosive charge, such as the igniter 37, in the event there has been a misfiring initially and a sharp downward force should be imparted to the second connection means 117. In the disarmed condition, the collapsed firing pin assembly 115. allows the pulling tool 125 to move downwardly such that its dogs 123 will engage the fishing neck means 27. The engagement of the pulling tool 125 with the fishing neck means 27 thereby positively advises the operator at the surface that disarming of the firing pin assembly 1 15 has been effected.

A first co-engaging roll pin 141 and slot 143 guide the firing pin within the firing pin cage 131 and limit downward movement of the firing pin 105 with respect to the firing pin cage 131. The firing pin 105 encounters the top 145 of the firing pin cage to limit downward movement of the firing pin cage 131 with respect to the firing pin 105. The roll pin 141 is preferably a pin that extends through an aperture in the firing pin and extends far enough outwardly to engage the slot 143 on each side of the firing pin 105. A second co-engaging roll pin 149 and slot 151 serve to guide and limit relative longitudinal movement between the firing pin 105 and the firing pin skirt 133. The slot 151 provides more limited relative movement between the firing pin 105 and the firing pin skirt 133 than is allowed by the slot 143 between the firing pin 105 and the firing pin cage 131. The respective roll pins 141 and 149 and their co-engaging slots 143 and 151 keep the firing pin assembly together during removal and alleviate difficulties with having to reassemble the individual pieces after each firing attempt. Moreover, the slots are so sized that at the most elongate condition of the firing pin assembly 115, as effected by the roll pins 141 and 149 being in the nearest ends of their respective slots 143 and 151, alignment of the arming aperture 137 through the firing pin 105, the firing pin cage 131 and the firing pin skirt 133 is automatically effected to facilitate removal and replacement of the shear pin 135 for rearming of the firing pin assembly at the surface. Expressed otherwise, the arming aperture 137 is aligned so that the remnants of the shear pin may be punched from the arming aperture 137 and a new shear pin 135 inserted thereinto.

- The overall operation has been described with respect to FIG. 1. Detailed considerations will now be described. Assume the percussion firing head assembly has 'been assembled as illustrated in FIGS. 2-4 except that the guide pin 51, instead of being at the upper position 153, FIG. 7, is disposed at the lower position 155 and the slip means 49 are below the inverted cone 67, FIG. 3. A running tool 17 is attached to the fishing neck means 27 and the percussion firing head assembly is run into the well. As the percussion firing head assembly 11 moves downwardly in the conduit 23, the drag shoe means 47 tend to move upwardly, moving the guide pin 51 to the top 157 of a running slot 159. The running slot 159 maintains the slip means 49 in a position below the inverted cone 67. The path the guide pin 51 follows in the J-slot to reach the top 157 is indicated by the arrows 163. The J-slot is relatively conventional and need not be described in detail herein. The running slot 159 and the preparatory slot are somewhat elongated in order to allow for variations in speed in the wellbore and to better keep the guide pin in the desired slot. When the desired depth has been reached, the running tool 17 is stopped and pulled upwardly. The guide pin 51 is moved to the bottom 167 of the preparatory slot 165 by the downward frictional dragging force of the drag shoes 57 against the conduit 23. Thereafter, the running tool 17 is again lowered.

The drag shoe means move upwardly, moving the guide pin 51 to the top 153 of the upwardly extending slot 65, or as far as the slip means will allow before they engage the walls of the conduit 23. Ordinarily, the slip means will engage the conduit 23 before the guide pin 51 reaches the top 153. Thus, the percussion firing head assembly is set in the well. Further downward force merely serves to set it more tightly in the well. By pulling the percussion firing head assembly 11 upwardly, however, the operator can release the slip means 49. The operator can safely set and release the slip means 419 as many times as necessary to obtain the desired setting depth; since there is no firing pin assembly 115 in the firing pin assembly receiving chamber 29 and the igniter means 31 cannot be fired. The shear down running tool 17 is jarred downwardly to shear its shear pin and disengage the fishing neck means 27. The running tool 17 is thereafter pulled from the well.

At the surface a shear up pulling tool 125 is attached to the tool string 19 and an armed firing pin assembly 115 is connected to the lower end of the pulling tool 125. The pulling tool 125 and the armed firing pin assembly 115 are then run into the well. The firing pin assembly 115 is run through the fishing neck means 27 and emplaced in the firing pin assembly receiving chamber 29 of the previously set percussion firing head assembly 11, as illustrated in FIG. 5. The pulling tool 125 is jarred downwardly to ignite the igniter 37. A shear up" pulling tool 125 is employed in order to allow the operator to jar downwardly as many times and with as great a force as needed without risking shearing a shear pin in the pulling tool when attempting to fire the igniter 37. Specifically, the downward jarring produces a sharp downward force that is great enough to first shear the shear pin 135 between the firing pin cage 131 and the firing pin skirt 133, and impart a sharp downward force of a fairly large magnitude to the firing pin 105. The firing pin 105 moves downwardly and strikes the hammer pin 73, causing the tip 77 to dent the safety disc 33, detonate the percussion cap 79 and fire the igniter 37. The shock wave from the igniter 37 travels down the detonation passageway 107 and detonates the booster pellet 111. The booster pellet 1111 then ignites a charge in the setting tool 13 which sets the bridge plug 15. The sharp downward force then shears shear pin 135 between the firing pin cage 131 and the firing pin 105 to disarm the firing pin assembly 115. While the sequential operation has been described hereinbefore, the entire operation occurs practically instantaneously as a result of one sharp downward force.

The firing pin assembly 115 is now disarmed and the structure collapses, allowing the dogs 123 of the pulling tool 125 to move downwardly beneath the fishing neck means 27. Thus, the pulling tool 125 is connected with the percussion firing head assembly. Even if there has been a misfiring, there is no danger of subsequent firing of the igniter 37; since the firing pin assembly 115 has been disarmed and the firing pin 105 is no longer responsive to the second connection means 117, and the unsheared safety disc 38 prevents the weight of the firing and hammer pins 105 and 73 from firing the igniter 37.

The shear up pulling tool then pulls the inverted cone 67 from beneath the slip means 49 to disengage the slip means and allow the percussion firing head assembly 11 to be drawn upwardly. As the inverted cone 67 is pulled upwardly, the drag shoe means 4-7 and the guide pin 51 move downwardly to the lower position 155, FIG. 7. The pulling tool 125, the percussion firing head assembly 11, the disarmed firing pin assembly 115, and the setting tool 13 are thereafter withdrawn from the well. A shear up pulling tool is also employed to allow the pulling tool 125 to be released from the percussion firing head assembly 1 1 in the event one or more of the tools should become immobilized, as by collapsed casing or debris in conjunction with failure of setting tool 13 to shear off of the bridge plug 15. In such an event, the released pulling tool 125 is pulled from the wellbore 25 and a stronger pulling apparatus is employed to fish out the percussion firing head assembly 1 1 and the setting tool 13.

At the surface the firing pin assembly is rearmed as indicated hereinbefore; that is, by extending it to its most elongate condition, punching out the shear pin and inserting a new shear pin 135. At the surface, the sub 45 may be unscrewed from the receiver 43 and the ejector cap 11 lifted upwardly, removing the igniter 37, whether it has been fired or not. A new igniter 37 may be emplaced in the ejector cap 41 and the tool reassembled as illustrated in FIG. 2, for an additional firing run in the same or different wellbore.

Although in the embodiment described and illustrated hereinbefore, a setting tool is shown as the device to be actuated responsive to firing, or ignition, of the igniter means, it should be understood that the invention may be utilized with various such devices, as for example, jet perforating guns and cut-off tools.

The materials of construction that are ordinarily employed in this art are satisfactory herein and no exotic new material need be employed.

From the foregoing descriptive matter it can be seen that this invention provides one or more of the desirable features delineated hereinbefore and not heretofore provided. Specifically, the invention provides the safety features of: (1) having a percussion firing apparatus that requires two trips to effect a firing; (2) preventing accidental firing by insertion of an armed firing pin assembly and a running tool simultaneously; (3) preventing engagement of a pulling tool until the firing pin assembly has been disarrned, thereby affording positive information to an operator at the surface that a firing attempt has been completed and that the percussion firing assembly can be safely pulled upwardly; and (4) permitting only one attempt to fire the igniter means and thereafter effecting a disarmed condition to prevent any improper later firing in the event there has been a misfire.

The percussion firing apparatus may be employed in conjunction with any of the conventional means for suspending it in a well at a predetermined depth; such as, suspending it via a string of tubing or via emplacement on a landing nipple or the like; whether or not such other means are as convenient and as generally available as the example, or embodiment, disclosed. Moreover, the separate, or second, trip of the firing pin means, or assembly, may be effected by any other conventional means; such as dropping it from the wellhead at the surface into its receiving chamber.

Although the invention has been described with a certain degree of particularity, it is understood that the present disclosure has been made only by way of example and that numerous changes in the details of construction and the combination and arrangement of parts may be resorted to without departing from the spirit and the scope of the invention.

What is claimed is:

l. Percussion firing apparatus for firing an explosive charge means within a well penetrating subterranean formations comprising:

a. a percussion firing head assembly including:

i. fishing neck means disposed at the upper end of said firing head assembly, adapted for being suspended from a shear down wireline running tool and adapted for being engaged and pulledupwardly by a shear up" pulling tool;

ii. firing pin assembly receiving chamber disposed adjacent said fishing neck means for receiving a firing pin assembly;

iii. means preventing receiving an armed firing pin assembly and said running tool simultaneously;

iv. igniter means disposed beneath said firing pin assembly receiving chamber so as to be ignited responsive to a downwardly moved firing pin in a firing pin assembly emplaced in said firing pin assembly receiving chamber;

v. settable hanging means for suspending said percussion firing head assembly in a conduit within said well; said hanging means being set by a downward force and released by an upward force; and

vi. first connection means for connection with a device that is actuated responsive to firing of said igniter means;

. a firing pin assembly that is adapted to be inserted through said fishing neck means and within said firing pin assembly receiving chamber and including:

i. second connection means disposed at the upper end of said firing pin assembly and adapted for connection with a wireline tool that is capable of transmitting a sharp downward force;

ii. a firing pin disposed within said firing pin assembly; and

iii. arming means connecting said firing pin with said second connection means such that said firing pin can be forced downwardly by a sharp downward force on said second connection means as by jarring downwardly on said wireline tool.

2. The percussion firing apparatus of claim 1 wherein a hammer'pin means is disposed intermediate said firing pin assembly and said igniter means so as to be struck by said downwardly moved firing pin for ignition of said igniter means; said firing pin being disposed so as to strike said hammer pinmeans when said firing pin assembly is emplaced within said firing pin assembly receiving chamber and said firing pin is subjected to said sharp downward force.

3. The percussion firing apparatus of claim 1 wherein an elongate detonation passageway is disposed intermediate said igniter means and said first connection means for downward passage of the shock wave from the ignited igniter means; and wherein a shooting adapter and a booster pellet are connected'with said first connection means and have a third connection means similar to said first connection means for connecting with a device that is actuated responsive to firing of said booster pellet.

4. The percussion firing apparatus of claim 1 wherein said means preventing receiving an armed firing pin assembly and said running tool simultaneously comprises a firing pin assembly receiving chamber of a first length L that is so short that said firing pin assembly, having a second length L from its said second connection means to its lower end when armed, cannot fit therewithin so as to allow said running tool to engage said fishing neck means when said armed firing pin assembly is within said firing pin assembly receiving chamber.

5. The percussion firing apparatus of claim 1 wherein said firing pin assembly includes a single-fire safety means interposed intermediate said firing pin and said second connection means; said single-fire safety meaps allowing arming said firing pin assembly such that said sharp downward force on said second connection means will cause said firing pin to attempt ignition of said igniter means; said single-fire safety means also effecting disarming of said firing pin assembly after one said attempt.

6. Percussion firing apparatus for firing an explosive charge means within a well penetrating subterranean formations comprising:

a. a percussion firing head assembly including:

i. fishing neck means disposed at the upper end of said firing head assembly, adapted for being suspended from a shear down wireline running tool and adapted for being engaged and pulled upwardly by a shear up" pulling tool;

ii. firing pin assembly receiving chamber disposed adjacent said fishing neck means for receiving a firing pin assembly;

iii. igniter means disposed beneath said firing pin assembly receiving chamber so as to be ignited responsive to a downwardly moved firing pin in a firing pin assembly emplaced in said firing pin assembly receiving chamber;

iv. settable hanging means for suspending said percussion firing head assembly in a conduit within said well; said hanging means being set by a downward force and released by an upward force; and

v. first connection means for connection with a device that is actuated responsive to firing of said igniter means;

. a firing pin assembly that is adapted to be inserted through said fishing neck means and within said firing pin assembly receiving chamber and including:

i. second connection means disposed at the upper end of said firing pin assembly and adapted for connection with a shear up wireline pulling tool that is capable of transmitting a sharp downward force;

ii. armed-safety means for preventing said pulling tool from engaging said second connection means and said fishing neck means of said percussion firing head assembly simultaneously;

iii. a firing pin disposed within said firing pin assembly; and

iv. arming means connecting said firing pin with said second connection means such that said firing pin can be forced downwardly by a sharp downward force on said second connection means as by jarring downwardly on said pulling tool.

7. The percussion firing apparatus of claim 6 wherein a hammer pin means is disposed intermediate said firing pin assembly and said igniter means so as to be struck by said downwardly moved firing pin for ignition of said igniter means; said firing pin being disposed so as to strike said hammer pin means when said firing pin assembly is emplaced within said firing pin assembly receiving chamber and said firing pin is subjected to said sharp downward force. a

8. The percussion firing apparatus of claim 6 wherein an elongate detonation passageway is disposed intermediate said igniter means and said first connection means for downward passage of the shock wave from the ignited igniter means; and wherein a shooting adapter and a booster pellet are connected with said first connection means and have a third connection means similar to said first connection means for connecting with a device that is actuated responsive to firing of said booster pellet.

9. The percussion firing apparatus of claim 6 wherein said armed safety means comprises a firing pin assembly receiving chamber of a first length L and said arming means and said firing pin assembly having a second length L when said firing pin assembly is armed such that engagement of said pulling tool with said fishing neck means is prevented until said arming means is disarmed.

10. The percussion firing apparatus of claim 9 wherein said length L is sufficiently great compared to the length L that engagement of said wireline running tool with said fishing neck means is also prevented if said firing pin assembly is armed and is emplaced within said firing pin assembly receiving chamber.

11. The percussion firing apparatus of claim 9 wherein said arming means and said firing pin are connected together to form a collapsible structure that is longer when armed than when disarmed.

12. Percussion firing apparatus for firing an explosive charge means within a well penetrating subterranean formations comprising:

a. a percussion firing head assembly including:

i. fishing neck means disposed at the upper end of said firing head assembly, adapted for being suspended from a running too], and adapted for being engaged and pulled upwardly by a pulling tool;

. firing pin assembly receiving chamber disposed adjacent said fishing neck means for receiving a firing pin assembly; said firing pin assembly receiving chamber having a first length L iii. igniter means disposed beneath said firing pin assembly receiving chamber so as to be ignited responsive to a downwardly moved firing pin in a firing pin assembly emplaced in said firing pin assembly receiving chamber; said igniter means including an igniter and a receiver for holding said igniter;

iv. settable hanging means for suspending said percussion firing head assembly in a conduit within said well; said hanging means being set by a downward force and released by an upward force; and

v. first connection means for connection with a device that is actuated responsive to firing of said igniter;

. a firing pin assembly that is adapted to be inserted through said fishing neck means and within said firing pin assembly receiving chamber and includmg:

i. second connection means disposed at the upper end of said firing pin assembly for connection with a borehole tool that is capable of trans mitting a sharp downward fiorce;

ii. a firing pin cage connected with said second connection means and adapted to slidably receive a firing pin;

iii. a firing pin slidably disposed adjacent said firing pin cage;

iv. a firing pin skirt slidably disposed adjacent said firing pin cage and having limited slidable movement longitudinally with respect to said firing pin; said firing pin skirt preventing physical in teraction between said firing pin and said igniter means prior to downward movement of said firing pin with respect to said firing pin skirt;

v. shear pin means extending through an arming aperture penetrating through said firing pin, said firing pin cage, and said firing pin skirt and cffecting a long combined length for the armed position of said firing pin assembly, said shear pin being adapted to shear first between said firing pin cage and said firing pin skirt which is resting on a non-moving portion of said percussion firing head assembly when said firing pin assembly is emplaced in said firing pin assembly receiving chamber; then to cause said firing pin to move downwardly to effect ignition of said igniter means responsive to a sharp downward force; and thereafter to shear between said firing pin cage and said firing pin to effect a disarmed firing pin assembly in which said firing pin is no longer responsively connected with said second 7 connection means.

13. The percussion firing apparatus of claim 12 wherein a hammer pin means is disposed intermediate said firing pin assembly and said igniter means so as to be struck by said downwardly moved firing pin for ignition of said igniter means; said firing pin being disposed so as to strike said hammer pin means when said firing pin assembly is emplaced within said firing pin assembly receiving chamber and said firing pin is subjected to said sharp downward force.

14. The percussion firing apparatus of claim 13 wherein said hammer pin means is disposed at the lower end of said firing pin assembly receiving chamber; said hammer pin means includes a hammer pin and a hammer pin retainer; said hammer pin being positioned so as to be struck by said downwardly moved firing pin.

15. The percussion firing apparatus of claim 14 wherein slot means are disposed adjacent said hammer pin retainer and communicate from the interior to the exterior of said percussion firing apparatus; and wherein said hammer pin retainer includes downwardly and outwardly inclined surfaces for draining off trash, debris, and the like for ensuring admission of said firing pin.

16. The percussion firing apparatus of claim 12 I wherein an elongate detonation passageway is disposed intermediate said igniter means and said first connec tion means for downward passage of the shock wave from the ignited igniter means; and wherein a shooting adapter and a booster pellet are connected with said first connection means and have a third connection means similar to said first connection means for connecting with a device that is actuated responsive to firing of said booster pellet.

17. The percussion firing apparatus of claim 12 wherein said firing pin is disposed concentrically within said firing pin cage and said firing pin skirt is disposed concentrically about said firing pin cage.

' 18. The percussion firing apparatus of claim 17 wherein said shear pin penetrates through said firing pin cage and said firing pin skirt on diametrally opposed sides of said firing pin.

19. The percussion firing apparatus of claim 17 wherein a first co-engaging roll pin and slot, guide said firing pin within said firing pin cage and limit downward movement of said firing pin with respect to said firing pin cage, and said firing pin encounters the top of said firing pin cage to limit downward movement of said firing pin cage with respect to said firing pin; and a second co-engaging roll pin and slot, guide and limit relative longitudinal movement between said firing pin and said firing pin skirt.

20. The percussion firing apparatus of claim 19 wherein said respective roll pins and their slots are positioned such that they effect at their most elongate position alignment of said arming aperture to facilitate removal and replacement of said shear pin means for rearming.

21. The percussion firing apparatus of claim 12 wherein said firing pin assembly in its armed position has a length L that is so related to length L, that it prevents the connection of said fishing neck means with a borehole tool when said firing pin assembly is armed and emplaced within said firing pin assembly receiving chamber.

22. The percussion firing. apparatus of claim 21 wherein L is longer than L 23. The percussion firing apparatus of claim 12 wherein said settable hanging means comprises drag shoe means and slip means; said drag shoe means having outwardly biased drag shoes for frictionally dragging on said conduit in said well and having a guide pin; wherein a J-slot is cut peripherally around a por tion of said percussion firing head assembly; said J-slot being continuous peripherally around said portion and engaging said guide pin for guiding said guide pin; said .l-slot having an entry slot for entry of said guide pin thereinto and having an elongate upwardly extending slot for allowing said slip means to be moved upwardly in response to appropriate downward movement of said percussion firing head assembly when said guide pin is aligned with said elongate upwardly extending slot; and wherein an inverted cone means is disposed adjacent said slip means when said slip means are at their lower 6 point; said inverted cone means being adapted for upward travel of said slip means thereon for extension of said slip means outwardly to engage the walls of said conduit in said well for hanging said percussion firing head assembly in said conduit.

24. The percussion firing apparatus of claim 12 wherein downward movement of said firing pin with respect to said. firing pin skirt allows said borehole tool to connect with said fishing neck means and advise an operator at the surface that disarming of said firing pin assembly has been effected. I

25. The percussion firing apparatus of claim 12 wherein a non-shearing safety disc means is disposed intermediate said igniter means and said firing pin assembly receiving chamber to prevent inadvertent firing of said igniter means.

26. Percussion firing apparatus for firing an explosive charge means within a well penetrating subterranean formations, having means for suspending a percussion firing head assembly at a predetermined depth comprising:

a. a percussion firing head assembly including:

i. firing pin assembly receiving chamber openat its upper end for receiving a firing pin assembly;

igniter means disposed beneath said firing pin assembly receiving chamber so as to be ignited responsive to a downwardly moved firing pin in a firing pin assembly received in saidfiring pin assembly receiving chamber; said igniter means including an igniter and a receiver for holding said igniter;

iii. connector means for connection with a device that is actuated responsive to firing of said igniter;

. a firing pin assembly that is adapted to be inserted within said firing pin assembly receiving chamber and including:

i. a firing pin cage adapted to slidably receive a firing pin;

ii. a firing pin slidably disposed adjacent said firing pin cage;

iii. a firing pin skirt slidably disposed adjacent said firing pin cage and having limited slidable movement longitudinally with respect to said firing pin; said firing pin skirt preventing physical interaction between said firing pin and said igniter means prior to downward movement of said firing pin with respect to said firing pin skirt;

iv. shear pin means extending through an arming aperture penetrating through said firing pin, said firing pin cage, and said firing pin skirt and effecting an armed position of said firing pin assembly, said shear pin being adapted to shear first between said firing pin cage and said firing pin skirt which contacts a non-moving portion of said percussion firing head assembly when said firing pin assembly is received in said firing pin assembly receiving chamber and subjected to sufficient downward force; thereby causing said firing pin to move downwardly to effect ignition of said igniter means; and thereafter to shear between said firing pin cage and said firing pin to effecta disarmed firing pin assembly.

27. The percussion firing apparatus of claim 26 wherein a hammer pin means is disposed intermediate said firing pin assembly and said igniter means so as to be struck by said downwardly moved firing pin for ignition of said igniter means; said firing pin being disposed so as to strike said hammer pin means when said firing pin assembly is received within said firing pin assembly receiving chamber and said firing pin is subjected to said downward force.

28. The percussion firing apparatus of claim 27 wherein said hammer pin means is disposed at the lower end of said firing pin assembly receiving chamber; said hammer pin means includes a hammer pin and a hammer pin retainer; said hammer pin being positioned so as to be struck by said downwardly moved firing pin.

29. The percussion firing apparatus of claim 28 wherein slot means are disposed adjacent said hammer pin retainer and communicate from the interior to the exterior of said percussion firing apparatus; and wherein said hammer pin retainer includes downwardly and outwardly inclined surfaces for draining off trash, debris, and the like for ensuring admission of said firing pin.

30. The percussion firing apparatus of claim 26 wherein an elongate detonation passageway is disposed intermediate said igniter means and said first connection means for downward passage of the shock wave from the ignited igniter means; and wherein a shooting adapter and a booster pellet are connected with said first connection means and have a third connection means similar to said first connection means for connecting with a device that is actuated responsive to firing of said booster pellet.

31. The percussion firing apparatus of claim 26 wherein said firing pin is disposed concentrically within said firing pin cage and said firing pin skirt is disposed concentrically about said firing pin cage.

32. The percussion firing apparatus of claim 31 wherein said shear pin penetrates through said firing pin cage and said firing pin skirt on diametrally opposed sides of said firing pin.

33. The percussion firing apparatus of claim 31 wherein a first co-engaging roll pin and slot, guide said firing pin within said firing pin cage and limit downward movement of said firing pin with respect to said firing pin cage, and said firing pin encounters the top of said firing pin cage to limit downward movement of said firing pin cage with respect to said firing pin; and a second co-engaging roll pin and slot, guide and limit relative longitudinal movement between said firing pin and said firing pin skirt.

34. The percussion firing apparatus ,of claim 33 wherein said respective roll pins and their slots are positioned such that they effect at their most elongate position alignment of said arming aperture to facilitate removal and replacement of said shear pin means for rearming.

35. The percussion firing apparatus of claim 26 wherein a non-shearing safety disc means is disposed intermediate said igniter means and said firing pin assembly receiving chamber to prevent inadvertent firing of said igniter means.

36. Percussion firing apparatus for firing an explosive charge means within a well, penetrating subterranean formations, having means for suspending a percussion firing head assembly at a predetermined depth, comprising:

a. a percussion firing head assembly including:

l. firing pm means receiving chamber open at its upper end for receiving a firing pin means that will be received on a separate trip after said percussion firing head assembly has been suspended at the predetermined depth;

ii. igniter means disposed beneath said firing pin means receiving chamber so as to be ignited responsive to a downwardly moved firing pin in said firing pin means receiv'ingchamber;

iii. connection means for connection with a device that is actuated responsive to firing of said igniter means;

b. a firing pin means including a firingpin that is movable into and longitudinally within said firing pin means receiving chamber so as to strike said hammer pin for igniting said igniter means;

c. a hammer pin means including a hammer pin and hammer pin retainer disposed at the lower end of said firing pin means receiving chamber and intermediate said firing pin means and said igniter means so as to be struck by said downwardly moved firing pin for ignition of said igniter means; said firing pin being disposed so as to strike said hammer pin when said firing pin means is received within said firing pin means receiving chamber and said firing pin is subjected to a sufficient downward force; and

d. slot means disposed adjacent said hammer pin retainer and communicating from the interior to the exterior of the bottom said firing pin means receiving chamber; said hammer pin retainer including downwardly and outwardly inclined surfaces for draining off trash, debris, and the like for ensuring that said firing pin will strike said hammer 

1. Percussion firing apparatus for firing an explosive charge means within a well penetrating subterranean formations comprising: a. a percussion firiNg head assembly including: i. fishing neck means disposed at the upper end of said firing head assembly, adapted for being suspended from a ''''shear down'''' wireline running tool and adapted for being engaged and pulled upwardly by a ''''shear up'''' pulling tool; ii. firing pin assembly receiving chamber disposed adjacent said fishing neck means for receiving a firing pin assembly; iii. means preventing receiving an armed firing pin assembly and said running tool simultaneously; iv. igniter means disposed beneath said firing pin assembly receiving chamber so as to be ignited responsive to a downwardly moved firing pin in a firing pin assembly emplaced in said firing pin assembly receiving chamber; v. settable hanging means for suspending said percussion firing head assembly in a conduit within said well; said hanging means being set by a downward force and released by an upward force; and vi. first connection means for connection with a device that is actuated responsive to firing of said igniter means; b. a firing pin assembly that is adapted to be inserted through said fishing neck means and within said firing pin assembly receiving chamber and including: i. second connection means disposed at the upper end of said firing pin assembly and adapted for connection with a wireline tool that is capable of transmitting a sharp downward force; ii. a firing pin disposed within said firing pin assembly; and iii. arming means connecting said firing pin with said second connection means such that said firing pin can be forced downwardly by a sharp downward force on said second connection means as by jarring downwardly on said wireline tool.
 2. The percussion firing apparatus of claim 1 wherein a hammer pin means is disposed intermediate said firing pin assembly and said igniter means so as to be struck by said downwardly moved firing pin for ignition of said igniter means; said firing pin being disposed so as to strike said hammer pin means when said firing pin assembly is emplaced within said firing pin assembly receiving chamber and said firing pin is subjected to said sharp downward force.
 3. The percussion firing apparatus of claim 1 wherein an elongate detonation passageway is disposed intermediate said igniter means and said first connection means for downward passage of the shock wave from the ignited igniter means; and wherein a shooting adapter and a booster pellet are connected with said first connection means and have a third connection means similar to said first connection means for connecting with a device that is actuated responsive to firing of said booster pellet.
 4. The percussion firing apparatus of claim 1 wherein said means preventing receiving an armed firing pin assembly and said running tool simultaneously comprises a firing pin assembly receiving chamber of a first length L1 that is so short that said firing pin assembly, having a second length L2 from its said second connection means to its lower end when armed, cannot fit therewithin so as to allow said running tool to engage said fishing neck means when said armed firing pin assembly is within said firing pin assembly receiving chamber.
 5. The percussion firing apparatus of claim 1 wherein said firing pin assembly includes a single-fire safety means interposed intermediate said firing pin and said second connection means; said single-fire safety means allowing arming said firing pin assembly such that said sharp downward force on said second connection means will cause said firing pin to attempt ignition of said igniter means; said single-fire safety means also effecting disarming of said firing pin assembly after one said attempt.
 6. Percussion firing apparatus for firing an explosive charge means within a well penetrating subterranean formations comprising: a. a percussion firing head assembly including: i. fishing neck means disposed at the upper end of said firing head assembly, adapted for being suspended from a ''''shear down'''' wireline running tool and adapted for being engaged and pulled upwardly by a ''''shear up'''' pulling tool; ii. firing pin assembly receiving chamber disposed adjacent said fishing neck means for receiving a firing pin assembly; iii. igniter means disposed beneath said firing pin assembly receiving chamber so as to be ignited responsive to a downwardly moved firing pin in a firing pin assembly emplaced in said firing pin assembly receiving chamber; iv. settable hanging means for suspending said percussion firing head assembly in a conduit within said well; said hanging means being set by a downward force and released by an upward force; and v. first connection means for connection with a device that is actuated responsive to firing of said igniter means; b. a firing pin assembly that is adapted to be inserted through said fishing neck means and within said firing pin assembly receiving chamber and including: i. second connection means disposed at the upper end of said firing pin assembly and adapted for connection with a ''''shear up'''' wireline pulling tool that is capable of transmitting a sharp downward force; ii. armed safety means for preventing said pulling tool from engaging said second connection means and said fishing neck means of said percussion firing head assembly simultaneously; iii. a firing pin disposed within said firing pin assembly; and iv. arming means connecting said firing pin with said second connection means such that said firing pin can be forced downwardly by a sharp downward force on said second connection means as by jarring downwardly on said pulling tool.
 7. The percussion firing apparatus of claim 6 wherein a hammer pin means is disposed intermediate said firing pin assembly and said igniter means so as to be struck by said downwardly moved firing pin for ignition of said igniter means; said firing pin being disposed so as to strike said hammer pin means when said firing pin assembly is emplaced within said firing pin assembly receiving chamber and said firing pin is subjected to said sharp downward force.
 8. The percussion firing apparatus of claim 6 wherein an elongate detonation passageway is disposed intermediate said igniter means and said first connection means for downward passage of the shock wave from the ignited igniter means; and wherein a shooting adapter and a booster pellet are connected with said first connection means and have a third connection means similar to said first connection means for connecting with a device that is actuated responsive to firing of said booster pellet.
 9. The percussion firing apparatus of claim 6 wherein said armed safety means comprises a firing pin assembly receiving chamber of a first length L1 and said arming means and said firing pin assembly having a second length L2 when said firing pin assembly is armed such that engagement of said pulling tool with said fishing neck means is prevented until said arming means is disarmed.
 10. The percussion firing apparatus of claim 9 wherein said length L2 is sufficiently great compared to the length L1 that engagement of said wireline running tool with said fishing neck means is also prevented if said firing pin assembly is armed and is emplaced within said firing pin assembly receiving chamber.
 11. The percussion firing apparatus of claim 9 wherein said arming means and said firing pin are connected together to form a collapsible structure that is longer when armed than when disarmed.
 12. Percussion firing apparatus for firing an explosive charge means within a well penetrating subterranean formations comprising: a. a percussion firing head assembly including: i. fishing neck means disposed at the upper end of said firing head assembly, adapted for being suspended from a running tool, and adapted for being engaged and pulled upwardly by a pulling tool; ii. firing pin assembly receiving chAmber disposed adjacent said fishing neck means for receiving a firing pin assembly; said firing pin assembly receiving chamber having a first length L1; iii. igniter means disposed beneath said firing pin assembly receiving chamber so as to be ignited responsive to a downwardly moved firing pin in a firing pin assembly emplaced in said firing pin assembly receiving chamber; said igniter means including an igniter and a receiver for holding said igniter; iv. settable hanging means for suspending said percussion firing head assembly in a conduit within said well; said hanging means being set by a downward force and released by an upward force; and v. first connection means for connection with a device that is actuated responsive to firing of said igniter; b. a firing pin assembly that is adapted to be inserted through said fishing neck means and within said firing pin assembly receiving chamber and including: i. second connection means disposed at the upper end of said firing pin assembly for connection with a borehole tool that is capable of transmitting a sharp downward force; ii. a firing pin cage connected with said second connection means and adapted to slidably receive a firing pin; iii. a firing pin slidably disposed adjacent said firing pin cage; iv. a firing pin skirt slidably disposed adjacent said firing pin cage and having limited slidable movement longitudinally with respect to said firing pin; said firing pin skirt preventing physical interaction between said firing pin and said igniter means prior to downward movement of said firing pin with respect to said firing pin skirt; v. shear pin means extending through an arming aperture penetrating through said firing pin, said firing pin cage, and said firing pin skirt and effecting a long combined length for the armed position of said firing pin assembly, said shear pin being adapted to shear first between said firing pin cage and said firing pin skirt which is resting on a non-moving portion of said percussion firing head assembly when said firing pin assembly is emplaced in said firing pin assembly receiving chamber; then to cause said firing pin to move downwardly to effect ignition of said igniter means responsive to a sharp downward force; and thereafter to shear between said firing pin cage and said firing pin to effect a disarmed firing pin assembly in which said firing pin is no longer responsively connected with said second connection means.
 13. The percussion firing apparatus of claim 12 wherein a hammer pin means is disposed intermediate said firing pin assembly and said igniter means so as to be struck by said downwardly moved firing pin for ignition of said igniter means; said firing pin being disposed so as to strike said hammer pin means when said firing pin assembly is emplaced within said firing pin assembly receiving chamber and said firing pin is subjected to said sharp downward force.
 14. The percussion firing apparatus of claim 13 wherein said hammer pin means is disposed at the lower end of said firing pin assembly receiving chamber; said hammer pin means includes a hammer pin and a hammer pin retainer; said hammer pin being positioned so as to be struck by said downwardly moved firing pin.
 15. The percussion firing apparatus of claim 14 wherein slot means are disposed adjacent said hammer pin retainer and communicate from the interior to the exterior of said percussion firing apparatus; and wherein said hammer pin retainer includes downwardly and outwardly inclined surfaces for draining off trash, debris, and the like for ensuring admission of said firing pin.
 16. The percussion firing apparatus of claim 12 wherein an elongate detonation passageway is disposed intermediate said igniter means and said first connection means for downward passage of the shock wave from the ignited igniter means; and wherein a shooting adapter and a booster pellet are connected with said first connection means and have a third connectiOn means similar to said first connection means for connecting with a device that is actuated responsive to firing of said booster pellet.
 17. The percussion firing apparatus of claim 12 wherein said firing pin is disposed concentrically within said firing pin cage and said firing pin skirt is disposed concentrically about said firing pin cage.
 18. The percussion firing apparatus of claim 17 wherein said shear pin penetrates through said firing pin cage and said firing pin skirt on diametrally opposed sides of said firing pin.
 19. The percussion firing apparatus of claim 17 wherein a first co-engaging roll pin and slot, guide said firing pin within said firing pin cage and limit downward movement of said firing pin with respect to said firing pin cage, and said firing pin encounters the top of said firing pin cage to limit downward movement of said firing pin cage with respect to said firing pin; and a second co-engaging roll pin and slot, guide and limit relative longitudinal movement between said firing pin and said firing pin skirt.
 20. The percussion firing apparatus of claim 19 wherein said respective roll pins and their slots are positioned such that they effect at their most elongate position alignment of said arming aperture to facilitate removal and replacement of said shear pin means for rearming.
 21. The percussion firing apparatus of claim 12 wherein said firing pin assembly in its armed position has a length L2 that is so related to length L1 that it prevents the connection of said fishing neck means with a borehole tool when said firing pin assembly is armed and emplaced within said firing pin assembly receiving chamber.
 22. The percussion firing apparatus of claim 21 wherein L2 is longer than L1.
 23. The percussion firing apparatus of claim 12 wherein said settable hanging means comprises drag shoe means and slip means; said drag shoe means having outwardly biased drag shoes for frictionally dragging on said conduit in said well and having a guide pin; wherein a J-slot is cut peripherally around a portion of said percussion firing head assembly; said J-slot being continuous peripherally around said portion and engaging said guide pin for guiding said guide pin; said J-slot having an entry slot for entry of said guide pin thereinto and having an elongate upwardly extending slot for allowing said slip means to be moved upwardly in response to appropriate downward movement of said percussion firing head assembly when said guide pin is aligned with said elongate upwardly extending slot; and wherein an inverted cone means is disposed adjacent said slip means when said slip means are at their lower point; said inverted cone means being adapted for upward travel of said slip means thereon for extension of said slip means outwardly to engage the walls of said conduit in said well for hanging said percussion firing head assembly in said conduit.
 24. The percussion firing apparatus of claim 12 wherein downward movement of said firing pin with respect to said firing pin skirt allows said borehole tool to connect with said fishing neck means and advise an operator at the surface that disarming of said firing pin assembly has been effected.
 25. The percussion firing apparatus of claim 12 wherein a non-shearing safety disc means is disposed intermediate said igniter means and said firing pin assembly receiving chamber to prevent inadvertent firing of said igniter means.
 26. Percussion firing apparatus for firing an explosive charge means within a well penetrating subterranean formations, having means for suspending a percussion firing head assembly at a predetermined depth comprising: a. a percussion firing head assembly including: i. firing pin assembly receiving chamber open at its upper end for receiving a firing pin assembly; ii. igniter means disposed beneath said firing pin assembly receiving chamber so as to be ignited responsive to a downwardly moved firing pin in a firing piN assembly received in said firing pin assembly receiving chamber; said igniter means including an igniter and a receiver for holding said igniter; iii. connector means for connection with a device that is actuated responsive to firing of said igniter; b. a firing pin assembly that is adapted to be inserted within said firing pin assembly receiving chamber and including: i. a firing pin cage adapted to slidably receive a firing pin; ii. a firing pin slidably disposed adjacent said firing pin cage; iii. a firing pin skirt slidably disposed adjacent said firing pin cage and having limited slidable movement longitudinally with respect to said firing pin; said firing pin skirt preventing physical interaction between said firing pin and said igniter means prior to downward movement of said firing pin with respect to said firing pin skirt; iv. shear pin means extending through an arming aperture penetrating through said firing pin, said firing pin cage, and said firing pin skirt and effecting an armed position of said firing pin assembly, said shear pin being adapted to shear first between said firing pin cage and said firing pin skirt which contacts a non-moving portion of said percussion firing head assembly when said firing pin assembly is received in said firing pin assembly receiving chamber and subjected to sufficient downward force; thereby causing said firing pin to move downwardly to effect ignition of said igniter means; and thereafter to shear between said firing pin cage and said firing pin to effect a disarmed firing pin assembly.
 27. The percussion firing apparatus of claim 26 wherein a hammer pin means is disposed intermediate said firing pin assembly and said igniter means so as to be struck by said downwardly moved firing pin for ignition of said igniter means; said firing pin being disposed so as to strike said hammer pin means when said firing pin assembly is received within said firing pin assembly receiving chamber and said firing pin is subjected to said downward force.
 28. The percussion firing apparatus of claim 27 wherein said hammer pin means is disposed at the lower end of said firing pin assembly receiving chamber; said hammer pin means includes a hammer pin and a hammer pin retainer; said hammer pin being positioned so as to be struck by said downwardly moved firing pin.
 29. The percussion firing apparatus of claim 28 wherein slot means are disposed adjacent said hammer pin retainer and communicate from the interior to the exterior of said percussion firing apparatus; and wherein said hammer pin retainer includes downwardly and outwardly inclined surfaces for draining off trash, debris, and the like for ensuring admission of said firing pin.
 30. The percussion firing apparatus of claim 26 wherein an elongate detonation passageway is disposed intermediate said igniter means and said first connection means for downward passage of the shock wave from the ignited igniter means; and wherein a shooting adapter and a booster pellet are connected with said first connection means and have a third connection means similar to said first connection means for connecting with a device that is actuated responsive to firing of said booster pellet.
 31. The percussion firing apparatus of claim 26 wherein said firing pin is disposed concentrically within said firing pin cage and said firing pin skirt is disposed concentrically about said firing pin cage.
 32. The percussion firing apparatus of claim 31 wherein said shear pin penetrates through said firing pin cage and said firing pin skirt on diametrally opposed sides of said firing pin.
 33. The percussion firing apparatus of claim 31 wherein a first co-engaging roll pin and slot, guide said firing pin within said firing pin cage and limit downward movement of said firing pin with respect to said firing pin cage, and said firing pin encounters the top of said firing pin cage to limit downward movement of said firing pin cage with respect to said firing pin; and a sEcond co-engaging roll pin and slot, guide and limit relative longitudinal movement between said firing pin and said firing pin skirt.
 34. The percussion firing apparatus of claim 33 wherein said respective roll pins and their slots are positioned such that they effect at their most elongate position alignment of said arming aperture to facilitate removal and replacement of said shear pin means for rearming.
 35. The percussion firing apparatus of claim 26 wherein a non-shearing safety disc means is disposed intermediate said igniter means and said firing pin assembly receiving chamber to prevent inadvertent firing of said igniter means.
 36. Percussion firing apparatus for firing an explosive charge means within a well penetrating subterranean formations, having means for suspending a percussion firing head assembly at a predetermined depth, comprising: a. a percussion firing head assembly including: i. firing pin means receiving chamber open at its upper end for receiving a firing pin means that will be received on a separate trip after said percussion firing head assembly has been suspended at the predetermined depth; ii. igniter means disposed beneath said firing pin means receiving chamber so as to be ignited responsive to a downwardly moved firing pin in said firing pin means receiving chamber; iii. connection means for connection with a device that is actuated responsive to firing of said igniter means; b. a firing pin means including a firing pin that is movable into and longitudinally within said firing pin means receiving chamber so as to strike said hammer pin for igniting said igniter means; c. a hammer pin means including a hammer pin and hammer pin retainer disposed at the lower end of said firing pin means receiving chamber and intermediate said firing pin means and said igniter means so as to be struck by said downwardly moved firing pin for ignition of said igniter means; said firing pin being disposed so as to strike said hammer pin when said firing pin means is received within said firing pin means receiving chamber and said firing pin is subjected to a sufficient downward force; and d. slot means disposed adjacent said hammer pin retainer and communicating from the interior to the exterior of the bottom said firing pin means receiving chamber; said hammer pin retainer including downwardly and outwardly inclined surfaces for draining off trash, debris, and the like for ensuring that said firing pin will strike said hammer pin. 